In general, there has been used a cutting/grinding fluid composition in the cutting/grinding processes. As the most important function of the cutting/grinding fluid composition, there can be listed, for instance, the lubricating action and the cooling action and these actions would permit the improvement of productivity such as the elongation of the service life of tools used in the metal working and the improvement of the precision of the finished plane of a subject to be processed and the improvement of the production efficiency.
It has been known, for a long time, that there are two types of metal working fluid compositions and more specifically, the non-water-soluble type one, on the one hand, which is used in the form of a stock solution and the water-soluble type one, on the other hand, which is used after it is diluted with water. In this respect, the use of the water-soluble type one has recently become the leading mainstream in this art while taking into consideration the saving of natural resources, the protection of the environment (working environment and the environment of the earth) and any risk of causing a fire.
The use of a water-soluble type metal working fluid composition would result in the reduction of the risk of causing a fire. On the contrary, in case of the water-soluble type metal working fluid composition, the organic components present therein should be diluted with water upon its practical use, and therefore, various problems arise such that microorganisms are easily proliferated in the diluted fluid composition, that the latter gives out bad smells due to the putrefaction thereof and that the quality thereof is accordingly impaired. For this reason, the diluted metal working fluid composition should frequently be replaced with fresh one within a short period of time and this in turn becomes a cause of the wasteful use of the natural resources and the pollution of the environment of the earth.
As means for solving the foregoing problems, there have been known, for instance, a water-soluble metal working fluid composition which makes use of peppermint oil (see Patent Document 1 specified below); a water-soluble metal working fluid composition which makes use of cinnamon oil (see Patent Document 2 specified below); a water-soluble metal working fluid composition which makes use of an aromatic amine or an alicyclic amine (see Patent Document 3 specified below); a water-soluble fluid composition for the grinding process, which makes use of a benzolic compound and a para-oxy-benzoic acid ester compound (see Patent Document 4 specified below); an antibacterial water-soluble fluid composition for the cutting process, which makes use of alkylene diamine (see Patent Document 5 specified below); a water-soluble fluid composition for the cutting process, which makes use of a fatty acid alkanolamide-ethylene oxide adduct and an alkylamine-ethylene oxide adduct, an alicyclic amine-ethylene oxide adduct or a fatty acid-higher alcohol adduct (see Patent Document 6 specified below); a water-soluble fluid composition for the cutting/grinding processes which makes use of a primary, secondary or tertiary alkylamine, aromatic diamine-oxyalkylene adduct, or an alicyclic diamine-oxyalkylene adduct (see Patent Document 7 specified below); a fluid composition comprising a primary alkanolamine, a carboxylic acid having 6 to 24 carbon atoms, and a specific alkylene-diamine (see Patent Document 8 specified below); and a microorganism-killing composition comprising, in combination, an N-substituted benzo-isothiazoline type compound (such as N-butylbenzoisothiazolin-3-one) and non-N-substituted benzo-isothiazoline type compound having a microorganism-killing action (such as bactericidal, fungicidal or algicidal actions) (see Patent Document 9 specified below).
However, any sufficient effect of preventing putrefaction of the fluid composition cannot be ensured through the use of these water-soluble metal working fluid compositions, or the metal working fluid compositions each showing such an effect make use of, for instance, a halogen atom-containing compound, a polycyclic aromatic compound, a phenolic compound or a metal salt. Some of them are compounds whose use is restricted by PRTR and the use thereof would be apprehensive of adversely affecting the human bodies.    Patent Document 1: JP No. 2,676,056;    Patent Document 2: JP No. 2,645,675;    Patent Document 3: JP No. 2,510,233;    Patent Document 4: JP-B-H07-037632;    Patent Document 5: JP-B-H07-030348;    Patent Document 6: JP-B-H06-031388;    Patent Document 7: JP-A-H09-316482;    Patent Document 8: JP-B-H06-076590;    Patent Document 9: JP-A-H10-298012.